|
Hi,
You might be asking the wrong person on here as I do all my own work and it’s not all that much automotive related even though I have a lots of personal vehicles.
About my past career as a journeyman machinist it was on an industrial scale.
I was raised with craftsmen and thinking that goes with it.
When you make things from scratch the part has to sell and the part talks to inspectors first and of course has to fit!
If you screw up something Lying that another “shift did it” can never be tolerated in the machining world.
During my career with one company we went from honor to having to use steel stamps and put our clock numbers around areas we finished.
A lot more paperwork because of ethics among the BS groups out there.
I hope your mechanic is not one of them.
From my world if that head needs to be machined flat again the journals may need to be recut. It’s not always the case or should not be in a properly maintained engine.
All out-of-line journals and caps have to be within a height tolerance to the face side.
There are specifications in our manuals for it and with lots of movement noted to save a head.
Valves have seat depths and cams have a height dimensions.
If you think about it all of the stuff up top is adjusted by shims and the whole cam is driven by a belt!
There are reasons for all of the adjustments being in there.
One is for mass production purposes or we couldn’t afford our cars.
Exotic cars are an example but we see them made for other budgets.
Not necessarily better but exclusive to an unrealistically small market group.
Their stuff filters down, if it’s worthy, otherwise, it’s not really needed anyway and is fools gold. 🤫
The automotive sector of machining is specialized to be akin to mass production and that is to be fast and simple.
The head probably could be bad but beyond their skill levels to repair it for a minimum set cost.
That last part truly runs wild in the automotive world of several domains over the years.
I need to ask what lead you to pull that head?
Once you let the hood be raised you need to get a definitive diagnosis.
Did you have the compression test done as I recommended?
What were any of those results indicating a malfunction?
A Coolant pressure test would tell if you had a bad head gasket.
You said in the original post 'ticking' at idle for quite a while now but always settled down and ran perfectly once up to speed.
Did something else go on later at a lower speed?
It’s my understanding that the engine was running fine except for a noise starting.
The engine head by itself is a piece of metal that doesn’t vibrate to make a noise. It hold things in place.
I don’t think even a cracked head causes noise unless you lose coolant or oil into combustion to make a spark knock. Even that can be managed some.
Fuel management does come into play here with speed. Just thinking out loud.
You have not said that you lost coolant or overheated the engine.
It takes some serious heat, several times to warp these engine heads and since it is bolted onto the block it won’t break a cam.
I’ll have to get more information on how that can work.
Now that he has undone the head was it less than .020 of an inch.
The maximum amount with the cam still installed.
I never take a cam out but it shouldn’t matter unless you really overheated it.
Most of the warp will be along or more across the axis. Or as the head twists at the corners. Not from end to end if it’s never been severely overheated.
A big hump in the in-line middle of .020 is a lot.
Did he show you what made him send it to the other shop?
You have to removed the valve components to spin the cam freely on oil in the those journals.
So, someone has to measure the cam bed or setup to them to machine the head flat. I do not know how that is achieved in head broachers since I never used one. Only seen pictures showing a cutter from underneath.
Normal is .006 to .010 warp and The cam can be held tighter due to the slight warping.
A used head has been repeatedly heated over many years.
It will normalize within these limits.
It’s one of several reasons for gaskets.
When a head is released from under the head bolts it will tighten up the cam because it’s still straight. You cannot expect less.
I’m curious who is BS ing who?
Have they offered a replacement head cost already? Maybe you need a second opinion but he’s got your hood up on his property. Ouch.
Since he got to get under the hood and you let him disassemble it you are set up to be paying his bills.
I don’t like what I’m saying either!
Since he sent the head in to the machine shop, he is putting the monkey on someone else’s back.
This way he can cover up if he was wrong and found the bad valve spring but see $$$ signs instead?
It appears that they, the other shop, maybe insinuating the engine head is warped beyond any recovery. Really?
You had better get with that shop to see if they even have it and get a lesson on head work and their noises.
Again, You might be asking the wrong man as I might be warped! 🤫
Did your mechanic remove cam caps first and look for oil starvation to the cam ?
Dry plain bearings cannot normally clack. It has no moving elements inside just an oil film.
A rotating cam cannot make a clacking noise as it’s solid, until broken, but that is not likely either.
I ask again, how did this happen when the engine never ran without any coolant loss before the noise started.
Since you are wanting to keep this car it doesn’t sound to me you would let it get overheated or knew that it had been.
How long have you owned the car, again?
Is this the same mechanic that was angling for a total rebuild because he thought it was a connecting rod?
I say this because if it was only one valve spring to change or a whole set it can be done on the engine from up top.
They put a little air upon the bad cylinder, to hold the valves up and slip things off the valves.
All the cylinders can be done. I recommended to test all springs for other weak ones.
I would expect either auto shop to do it to a head in order to guarantee the work.
Another side story involved my sister-in-laws 2006 Range Rover.
I’m afraid it’s going to sound similar to yours, so watch out.
She had a missing cylinder and the hood went up with a diagnosis of a bad head gasket on the right bank.
They removed the head and it was showing coolant leakage.
Then they said the left bank should be done to keep the engine in balance with ages of the gaskets.
Sounds logical since all the accessories and intake are already off.
After the machine work was done and assembly was started they noticed the same right side cylinder had a slipped liner in the block!
Down about .200 of an inch. They acted as liner were a surprise but he claimed that his new female mechanic saw it and he did not.
Further investigation said that the engine was made by Chevrolet for Range Rover.
Slipping liners a common problem with this special engine.
Now he wanted $3 to $5000 more to guarantee the repair it or a new engine that could be even more!
Upon my advise she paid him for work done and towed it home.
The vehicle was in pieces and put into the backend.
I think she was down about $2K to pay him off .
She ended up donating the vehicle to charity as I do not do that kind of work 600 miles from my car lift!
Besides it’s a RR that I had already had some moments with.
I did fixed her electric sliding sunroof by soldering up a relays internal board that is mounted up in the roofs headliner.
Guess… where I learned that trick, from 240s.
The RR dealer again wanted $800.
Before me she also got clipped for her ABS brakes needing new software for you guess it $800. It had to come from England to a representative here.
Range Rovers have lots of horror stories for something that appears so nice and rugged.
The nice gets ugly!
Complicated beyond belief electrically.
The alternators are used for RPMs to the tachometer by picking off a signal from a diode.
They already have a CPS for computer and ignition purposes. Just nuts.
Crazy prices for an alternator that no one wants to offer as a rebuilt at that time.
When her husband was alive he got took on a replacement two years before. $400+ from a parts house.
Luckily I located a rebuilder for this Marelli Italian unit @ $150 for her.
This rebuilder told me he tries to stay away from them for even more reasons.
Sorry, too long of a post but this is real life dealings and it helps to network.
Phil
|
